Citric Acid → 4-(5-methoxy-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide citrate

Participants

Reaction Steps

The polar diastereoisomer of 4-(5-methoxy-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide (197 mg, 0.403 mmole) was dissolved in abs. ethanol (3 ml) and DCM (5 ml). Citric acid (78.3 mg, 0.407 mmole) was added in one portion at ca. 40° C. while stirring. The reaction mixture was stirred for 2 hours at RT. During this time no precipitate formed. The solvents were distilled off down to a volume of 2 ml. Diethyl ether (30 ml) was added to the residue. The suspension was stirred for 20 hours at RT. The precipitate was filtered off, washed with diethyl ether (3×1.5 ml) and dried in vacuo. The polar diastereoisomer of 4-(5-methoxy-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide citrate (239 mg, m.p. 139°-143° C., 87%, Example 46) was a colourless solid.

Provenance & Evidence